Method for separating fibers and method for producing modacrylic fiber, polyvinyl chloride fiber and polyester fiber

The present invention relates to a method for separating a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber. In particular, the present invention relates to the method for separating the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, which is useful for recycling fibers used in artificial hairs.

Further, the present invention relates to a method for producing the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber.

Modacrylic fiber, polyvinyl chloride fiber, polyvinylidene chloride fiber, polyester fiber, nylon fiber, polypropylene fiber and the like are generally used as fiber for artificial hairs used in wigs, hair pieces, doll headdresses and the like.

Among them, modacrylic fiber, polyvinyl chloride fiber and polyester fiber are widely used as the fiber for the artificial hairs due to their characteristics.

Polyvinyl chloride resin has excellent self-extinguishing properties and chemical resistance and can have these excellent properties even when made into a fiber. When artificial hairs are worn on the head in various shapes, self-extinguishing properties are an important necessary property for safety.

In addition, artificial hairs using the polyvinyl chloride fiber has a feature that its appearance and texture are similar to human hairs and is also highly used for its cosmetic properties (For example, Patent Document 1).

On the other hand, modacrylic fiber obtained from modacrylic resin copolymerized with acrylonitrile and vinyl halide and/or vinylidene halide has advantage of being very similar to human hairs in texture, luster, and volume, as well as being easy to comb. Therefore, the modacrylic fiber has very excellent properties as fiber for artificial hairs (For example, Patent Documents 2 and 3).

In addition, polyester fiber whose main component is polyester resin, such as polyethylene terephthalate, have excellent heat resistance, making it possible to set curls using beauty heat equipment such as hair irons. Therefore, the polyester fiber have excellent properties as fiber for artificial hairs in that they can be adapted to various hairstyles (For example, Patent Document 4).

As quality of such artificial hairs improves, it is becoming as natural as human hairs, and its market is expanding. Therefore, the production amount of the artificial hairs is increasing year by year, and the amount of the artificial hairs that is discarded due to deterioration and the like is also increasing.

In recent years, as awareness of environmental issues has increased, synthetic fibers are also required to have recyclability. Therefore, there is a need for a method for separating various fiber mixtures collected and shredded by raw materials in the recycling process of fibers used in the artificial hairs.

However, as mentioned above, the artificial hairs is made from various fibers such as modacrylic fiber, polyvinyl chloride fiber, polyester fiber, polypropylene fiber and nylon fiber, and when disposed of the artificial hairs, these fibers are mixed together. Therefore, it is necessary to separate these fibers for recycling.

In particular, modacrylic fiber, polyvinyl chloride fiber and polyester fiber account for a large proportion of the artificial hairs, and it is important to separate these three fibers.

Accordingly, an object of the present invention is to provide a method for separating fibers that separates a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber.

In particular, an object of the present invention is to provide a simpler and lower-cost method for separating fibers.

The present invention also provides a method for producing these fibers using the modacrylic fiber, the polyvinyl chloride fiber or the polyester fiber separated by the above method.

In a method for separating a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber based on their differences in specific gravity, it has been found that simply by optimizing the specific gravity of a liquid used for separation, fibers float that on the liquid contrary to the specific gravity are generated, and these fibers sufficiently cannot be separated. The present inventor conducted studies to solve the above problems and found that the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber can be sufficiently separated by using a combination of a type of compound to optimize the specific gravity and a specific type of surfactant, and the present inventor has completed the present invention.

That is, the present invention relates to:

Further, the present invention relates to:

Further, the present invention relates to:

According to the present invention, there is provided a method for separating fibers that separates a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber from a fiber mixture containing at least two selected from the group consisting of these fibers. In particular, according to the present invention, a simpler and lower-cost separation method is provided.

Further, there is also provided a method for producing these fibers using a modacrylic fiber, a polyvinyl chloride fiber or a polyester fiber separated.

Hereinafter, the present invention will be explained based on its preferred embodiments.

A method for separating fibers of the present invention (hereinafter also referred to as “present separation method”) includes a step of mixing a mixture containing at least two selected from the group consisting of a modacrylic fiber, a polyvinyl chloride fiber and a polyester fiber, and a liquid mixture containing calcium chloride, a nonionic surfactant and water and separates fibers contained in the fiber mixture from the fiber mixture.

That is, the present separation method is a method for separating the modacrylic fiber and the polyvinyl chloride fiber in the case of a mixture containing the modacrylic fiber and the polyvinyl chloride fiber, a method for separating the modacrylic fiber and the polyester fiber in the case of a mixture containing the modacrylic fiber and the polyester fiber, a method for separating the polyvinyl chloride fiber and the polyester fiber in the case of a mixture containing the polyvinyl chloride fiber and the polyester fiber, or a method for separating the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber in the case of a mixture containing the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber.

As described above, the modacrylic fiber used in the present separation method is a fiber obtained from a modacrylic resin obtained by copolymerizing acrylonitrile with vinyl halide and/or vinylidene halide.

The polyvinyl chloride fiber used in the present separation method is a fiber obtained from a homopolymer of vinyl chloride or a polyvinyl chloride resin, which is a copolymer containing vinyl chloride as a main component.

The polyester fiber used in the present separation method is a fiber obtained from a polyester resin that is a condensation polymer of polyalcohol and polyhydric carboxylic acid. Examples of the polyalcohol include ethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,4-cyclohexanedimethanol.

Examples of the polyhydric carboxylic acid include terephthalic acid and 2,6-naphthalene dicarboxylic acid. As the polyester fiber, polyethylene terephthalate fiber obtained from polyethylene terephthalate resin, which is a condensation polymer of ethylene glycol and terephthalic acid, is preferable.

The mixture containing at least two selected from the group consisting of the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber (hereinafter also referred to as “present fiber mixture”) is a mixture containing the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber that are subject to collection and recycling, from which artificial hairs using these fibers has been discarded due to deterioration or consumption, and the mixture may contain components other than these fibers.

Components other the modacrylic the than fiber, polyvinyl chloride fiber and the polyester fiber include non-resin components contained in wigs, hair extensions, and the like containing artificial hairs, and their crushed materials, fibers and molded products made of resins other than the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber and the like. Examples of fibers made of resins other than the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber include a polypropylene fiber and a nylon fiber.

When the present mixture fiber contains components other than the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, it is preferable to remove these components in advance and subject it to the present separation method.

For example, when the present fiber mixture contains the modacrylic fiber and the polyvinyl chloride fiber and the mixture further contains metals or metal salts, a method may be used in which the metals or the metal salts are separated from the mixture containing the modacrylic fiber and the polyvinyl chloride fiber by dissolving, magnetic force, or the like.

Further, when the mixture containing the modacrylic fiber and the polyvinyl chloride fiber further contains polypropylene fibers or nylon fibers, a method may be used in which these fibers are separated from the mixture containing the modacrylic fiber and the polyvinyl chloride fiber by electrostatic separation or the like.

Even when the present fiber mixture contains the modacrylic fiber and the polyester fiber, the polyvinyl chloride fiber and the polyester fiber, or the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, the metals, the metal salts and other fibers can be separated from the mixture in the same manner as described above.

It is preferable that components other than those mentioned above be separated from the present fiber mixture by an appropriate separation method depending on their forms, raw materials, and the like, and then the mixture is subjected to the present separation method.

In the present separation method, when the fiber mixture contains components other than the modacrylic fiber, the polyvinyl chloride fiber and the polyester fibers, the present fiber mixture preferably contains a total of 70% by mass or more of at least two selected from the group consisting of the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, with the total mass of the fiber mixture being 100% by mass, more preferably 80% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass. When the present fiber mixture contains the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, the total amount of these fibers is preferably within the above range, with the total mass of the present fiber mixture being 100% by mass.

When the fibers contained in the present fiber mixture are the modacrylic fiber and the polyvinyl chloride fiber, as for a ratio of the modacrylic fiber to the polyvinyl chloride fiber, the mass of the polyvinyl chloride fiber is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 0.8 or more and 1.2 or less, with the mass of the modacrylic fiber being 1.

When the fibers contained in the present fiber mixture are the modacrylic fiber and the polyester fiber, as for a ratio of the modacrylic fiber to the polyester fiber, the mass of the polyester fiber is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 0.8 or more and 1.2 or less, with the mass of the modacrylic fiber being 1.

When the fibers contained in the present fiber mixture are the polyvinyl chloride fiber and the polyester fiber, as for a ratio of the polyvinyl chloride fiber to the polyester fiber, the mass of the polyester fiber is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 0.8 or more and 1.2 or less, with the mass of the polyvinyl chloride fiber being 1.

When the fibers contained in the present fiber mixture are the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, as for a ratio of the modacrylic fiber, the polyvinyl chloride fiber and the polyester fiber, the mass of the polyvinyl chloride fiber is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 0.8 or more and 1.2 or less, with the mass of the modacrylic fiber being 1. Similarly, the mass of the polyester fiber is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, and even more preferably 0.8 or more and 1.2 or less.

The present fiber mixture is mixed with a liquid mixture containing calcium chloride, a nonionic surfactant and water (hereinafter also referred to as “present liquid mixture”).

From the viewpoint of separation efficiency of the fibers and cleaning of the fibers after separation, the liquid mixture is preferably in the form of an aqueous solution in which the calcium chloride and the nonionic surfactant are uniformly dissolved.

It is thought that the calcium chloride contained in the present liquid mixture has a role of adjusting a specific gravity of the present liquid mixture to a specific gravity appropriate for separating the fibers contained in the present fiber mixture.

Although the details are unknown, it is thought that inorganic salts other than the calcium chloride, such as potassium carbonate, do not have sufficient compatibility with the nonionic surfactant, resulting in insufficient separation of the fibers in the present fiber mixture.

When the fibers contained in the present fiber mixture are the modacrylic fiber and the polyvinyl chloride fiber, from the viewpoint of adjusting the specific gravity of the present liquid mixture to an appropriate specific gravity for separating the modacrylic fiber and the polyvinyl chloride fiber, the specific gravity of the liquid mixture is preferably 1.25 or more and 1.40 or less, more preferably 1.27 or more and 1.36 or less, even more preferably 1.28 or more and 1.32 or less, and particularly preferably 1.29 or more and 1.31 or less.

When the fibers contained in the present fiber mixture are the modacrylic fiber and the polyester fiber, from the viewpoint of adjusting the specific gravity of the present liquid mixture to an appropriate specific gravity for separating the modacrylic fiber and the polyester fiber, the specific gravity of the liquid mixture is preferably 1.25 or more and 1.45 or less, more preferably 1.30 or more and 1.43 or less, even more preferably 1.35 or more and 1.42 or less, and particularly preferably 1.39 or more and 1.41 or less.

When the fibers contained in the present fiber mixture are the polyvinyl chloride fiber and the polyester fiber, from the viewpoint of adjusting the specific gravity of the present liquid mixture to an appropriate specific gravity for separating the polyvinyl chloride fiber and the polyester fiber, the specific gravity of the liquid mixture is preferably 1.35 or more and 1.45 or less, more preferably 1.37 or more and 1.43 or less, even more preferably 1.38 or more and 1.42 or less, and particularly preferably 1.39 or more and 1.41 or less.

When the fibers contained in the present fiber mixture are the modacrylic fiber, the polyvinyl chloride fiber and fiber, the polyester from the viewpoint of adjusting the specific gravity of the present liquid mixture to an appropriate specific gravity for separating the modacrylic fiber, the polyvinyl chloride and fiber the polyester fiber, the specific gravity of the liquid mixture is preferably 1.25 or more and 1.45 or less, more preferably 1.30 or more and 1.43 or less, even more preferably 1.35 or more and 1.42 or less, and particularly preferably 1.39 or more and 1.41 or less.

The content of the calcium chloride in the present liquid mixture is preferably in a range in which the calcium chloride is dissolved in the present liquid mixture, and from the viewpoint of the specific gravity of the present liquid mixture, the content of the calcium chloride in the present liquid mixture is more preferably 31% by mass or more and 34% by mass or less, with the mass of the present liquid mixture being 100% by mass.